Nonaqueous Battery Separator Pore Volume and Self-Discharge
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Solution Overview
Problem
Nonaqueous electrolyte batteries face issues with self-discharge and separator clogging due to the contact between positive and negative electrodes, which is exacerbated by the use of separators with low pore volume ratios of pores having diameters of 1 μm or more, leading to increased electrical resistance and reduced battery life.
Innovation Solution
A nonaqueous electrolyte battery design featuring a negative electrode with a Li-absorbing potential of 1 V vs. Li/Li+ or more and a separator with a pore volume ratio of pores having a diameter of 1 μm or more exceeding 70%, along with an electrical resistance of the negative electrode in a discharged state within 100 Ω·cm to 100000 Ω·cm, which inhibits separator clogging and self-discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator with a high ratio of pores having a pore diameter of 1 μm or more per unit volume is used, then long-term stabilization of the battery and impregnation with electrolyte solution are improved, but the positive electrode and negative electrode will probably come into contact, resulting in a cell with a large self-discharge amount
Solution Approach 1:
The invention changes the pore diameter parameter of the separator to be 0.03 μm or more but less than 1 μm, which is a significant deviation from conventional separators. This parameter change allows the separator to maintain high porosity (improving electrolyte impregnation and long-term stabilization) while preventing electrode contact (reducing self-discharge), thus resolving the technical contradiction.
2Quantity of substance
If a separator with a high ratio of pores having a pore diameter of 1 μm or more per unit volume is used, then impregnation with electrolyte solution is improved, but the positive electrode and negative electrode will probably come into contact
Solution Approach 1:
The invention optimizes the pore diameter parameter to be in the range of 0.03 μm or more and less than 1 μm. This specific parameter range enables the separator to achieve sufficient electrolyte impregnation while maintaining adequate mechanical strength to prevent electrode contact, thereby resolving the contradiction between substance penetration and structural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the battery's life characteristics and suppresses self-discharge, maintaining performance and preventing the negative electrode from becoming a discharge state that could lead to further self-discharge.
Implementation Method 1
a pore volume ratio of pores having a pore diameter of 1 μm or more in the separator is more than 70%
Implementation Method 2
The negative electrode contains a negative electrode active material having a Li-absorbing potential of 1 V vs. Li/Li+ or more
Implementation Method 3
a separator sandwiched between the positive electrode and the negative electrode
Data Source
AI summary
According to an embodiment, there is provided a nonaqueous electrolyte battery. The nonaqueous electrolyte battery includes a positive electrode, a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The negative electrode contains a negative electrode active material having a Li-absorbing potential of 1 V vs. Li/Li+ or more. An electrical resistance of the negative electrode in a discharged state is within a range of 100 Ω·cm to 100000 Ω·cm. A pore volume ratio of pores having a pore diameter of 1 μm or more in the separator is more than 70%. The pore volume ratio is determined from a cumulative pore volume frequency curve of the separator obtained by a mercury intrusion porosimetry.